CN110911336A

CN110911336A - Increasing gas efficiency for an electrostatic chuck

Info

Publication number: CN110911336A
Application number: CN201911241081.3A
Authority: CN
Inventors: V·D·帕科
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2014-09-12
Filing date: 2015-08-06
Publication date: 2020-03-24
Anticipated expiration: 2035-08-06
Also published as: KR102417007B1; WO2016039899A1; TWI673810B; CN106575635A; US20160079105A1; US20170329352A1; US20230350435A1; US9753463B2; KR20170051411A; JP2017530545A; JP6655600B2; KR20220028176A; US11747834B2; CN110911336B; TW201618214A; CN106575635B; KR102369247B1

Abstract

The invention relates to increasing gas efficiency for an electrostatic chuck. Gas is received through an inlet. A portion of the gas is supplied to the electrostatic chuck. Part of the gas is recirculated through the compressor. The pressure of the second portion of the gas is increased. A second portion of the gas is stored in the gas reservoir.

Description

Increasing gas efficiency for an electrostatic chuck

This application is a divisional application of the chinese patent application entitled "increasing gas efficiency for an electrostatic chuck" filed on date 2015 at 8/6, application No. 201580043978.9.

The present application claims the benefit of prior U.S. provisional patent application No. 62/049,963 entitled "increasing gas efficiency FOR ELECTROSTATIC CHUCKs (INCREASING THE GAS EFFICIENCY FOR AN ELECTROSTATIC CHUCK") filed on 12/9/2014 and U.S. non-provisional application No. 14/529,985 entitled "increasing gas efficiency FOR ELECTROSTATIC CHUCKs (INCREASING THE GAS EFFICIENCY FOR AN ELECTROSTATIC CHUCK)" filed on 31/10/2014, which are incorporated herein by reference in their entirety.

Technical Field

Embodiments of the invention relate to the field of electronic device manufacturing, and more particularly to providing gas to an electrostatic chuck.

Background

Generally, in a plasma processing system, photons, ions, and other particles impinge on and heat a wafer. For plasma processing, a wafer is placed on an electrostatic chuck in a processing chamber. Typically, a gas (e.g., helium) is used on the backside of the wafer to enhance heat transfer between the E-chuck (electrostatic chuck) and the wafer. To introduce the gas with low resistance, grooves are milled into the chuck. Gas that enters the grooves on the chuck diffuses under the wafer and may leak into the chamber under the wafer.

Typically, only a small portion of the helium backside gas (e.g., at a flow rate of about 0.5 standard cubic centimeters per minute (SCCM)) passes through the chuck due to the good seal between the polished outside sealing band on the chuck and the backside surface of the wafer. The majority of the backside helium (at a flow rate of about 19.5 SCCM) leaks out through the flow holes in the vacuum system. This is not an efficient method of using the backside expensive heat transfer gas.

Currently, due to government regulations and increased helium costs, many manufacturers are using gases other than helium (such as nitrogen and argon) as backside gases in electrostatic chucks. Nitrogen and argon have severe limitations in terms of electron ionization potential and thermal properties that may be unacceptable for some plasma tools.

In addition, argon and nitrogen backside gases have conduction paths and arcing problems under certain plasma conditions. These problems lead to the creation of defects (e.g., holes, imprints, other defects) and damage to the wafer, which greatly limits the plasma processing design and increases manufacturing costs.

Disclosure of Invention

Methods and apparatus for increasing the efficiency of a gas for an electrostatic chuck (e-chuck) are described. Gas is received through an inlet. A first portion of the gas is supplied to the e-chuck. A second portion of the gas is recirculated through the compressor.

In an embodiment, the gas is received through an inlet. A first portion of the gas is supplied to the e-chuck. A second portion of the gas is recirculated through the compressor. The pressure of the second portion of the gas is increased by the compressor. A second portion of the gas is stored in the gas reservoir.

In an embodiment, the gas is received through an inlet. A first portion of the gas is supplied to the e-chuck. A second portion of the gas is recirculated through the compressor. The gas is helium, argon, neon, krypton, xenon, other inert gases, nitrogen, or any combination of the above.

In an embodiment, the gas is received through an inlet. A first portion of the gas is supplied to the e-chuck. A second portion of the gas is supplied to the vacuum line through the flow aperture for a first time interval. A second portion of the gas is supplied to the recycle line for a second time interval to be delivered through the compressor.

In an embodiment, the gas is received through an inlet. A first portion of the gas is supplied to the e-chuck. A pressure set point for the first portion of the gas is determined. A calibration curve is obtained. Based on the difference between the total flow and the flow at that pressure from the calibration curve, the flow rate of the first portion of the gas supplied to the e-chuck for the pressure set point is calculated. A first portion of the gas supplied to the e-chuck is controlled based on the gas pressure and seal between an outer sealing band of the ESC and the back surface of the wafer. A second portion of the gas is recirculated through the compressor.

In an embodiment, the gas is received through the inlet with the first portion of the flow closed. The flow of gas at the plurality of pressure values when flowing only through the second portion is measured to generate a calibration curve. The first portion of the gas is supplied to the e-chuck at a flow rate estimated using the calibration curve. A second portion of the gas is recirculated through the compressor.

In an embodiment, the gas is received through an inlet. A first portion of the gas is supplied to the e-chuck. It is determined whether gas is supplied through the inlet. If gas is supplied to the inlet, a trigger signal is sent to the compressor. A second portion of the gas is recirculated through the compressor.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to supply a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to recirculate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to supply a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to recirculate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet. A compressor is coupled to the second outlet to increase the pressure of the second portion of the gas. A gas reservoir is coupled to the compressor to store a second portion of the gas.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to deliver a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to circulate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet. The gas is helium, argon, neon, krypton, xenon, other inert gases, nitrogen, or any combination of the above.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to supply a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to recirculate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet. The controller has a first configuration for controlling the supply of the second portion of the gas through the flow orifice to the vacuum line for a first time interval to calculate a flow rate in the first outlet. The controller has a second configuration for controlling the recirculation of a second portion of the gas for a second time interval.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to supply a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to recirculate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet. The controller has a third configuration for determining a pressure set point for the first portion of the gas. The controller has a fourth configuration for obtaining a calibration curve for the gas. The controller has a fifth configuration for estimating a flow rate of the first portion of the gas supplied to the e-chuck for the pressure set point based on the calibration curve. The controller has a sixth configuration for controlling the first portion of the gas based on the estimated flow rate.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to supply a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to recirculate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet. The controller has a seventh configuration for controlling the flow of the measured gas at a plurality of pressure values to generate a calibration curve. A first portion of the gas is supplied to the e-chuck using a calibration curve.

In an embodiment, a system for increasing the efficiency of a gas for an e-chuck includes an inlet for receiving the gas. A first outlet is coupled to the inlet to supply a first portion of the gas to the e-chuck. The second outlet is coupled to the first outlet to recirculate a second portion of the gas through the compressor. A controller is coupled to control at least one of the inlet, the first outlet, and the second outlet. The controller has an eighth configuration for controlling whether to determine whether to supply the gas through the inlet. The controller has a ninth configuration for controlling sending of a trigger signal to the compressor if gas is supplied to the inlet.

In an embodiment, a non-transitory machine-readable medium includes executable program instructions that, when executed by a data processing system, cause the data processing system to perform operations comprising: receiving a gas through an inlet; supplying a first portion of the gas to the e-chuck; and recycling a second portion of the gas through the compressor.

In an embodiment, a non-transitory machine-readable medium includes executable program instructions that, when executed by a data processing system, cause the data processing system to perform operations comprising: receiving a gas through an inlet; supplying a first portion of the gas to the e-chuck; recirculating a second portion of the gas through the compressor; increasing the pressure of the second portion of the gas by a compressor; and storing the second portion of the gas in the gas reservoir.

In an embodiment, a non-transitory machine-readable medium includes executable program instructions that, when executed by a data processing system, cause the data processing system to perform operations comprising: receiving a gas through an inlet; supplying a first portion of the gas to the e-chuck; supplying a second portion of the gas to the vacuum line through the flow aperture for a first time interval; and recirculating a second portion of the gas through the compressor for a second time interval.

In an embodiment, a non-transitory machine-readable medium includes executable program instructions that, when executed by a data processing system, cause the data processing system to perform operations comprising: receiving a gas through an inlet; supplying a first portion of the gas to the e-chuck; determining a pressure set point for a first portion of the gas; obtaining a calibration curve for the gas; estimating a flow rate of a first portion of the gas at the e-chuck for a pressure set point based on the calibration curve; and recycling a second portion of the gas through the compressor.

In an embodiment, a non-transitory machine-readable medium includes executable program instructions that, when executed by a data processing system, cause the data processing system to perform operations comprising: receiving a gas through an inlet; measuring a flow of gas at a plurality of pressure values to generate a calibration curve; supplying a first portion of the gas to the e-chuck at a flow rate determined using the calibration curve; and recycling a second portion of the gas through the compressor.

In an embodiment, a non-transitory machine-readable medium includes executable program instructions that, when executed by a data processing system, cause the data processing system to perform operations comprising: receiving a gas through an inlet; supplying a first portion of the gas to the e-chuck; determining whether to supply gas through the inlet; sending a trigger signal to the compressor if gas is supplied to the inlet; and recycling a second portion of the gas through the compressor.

Other features of embodiments of the present invention will be apparent from the accompanying drawings and from the detailed description that follows.

Drawings

Embodiments as described herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.

Fig. 1 illustrates an apparatus for increasing the efficiency of gas use for an electrostatic chuck according to one embodiment of the present invention.

FIG. 2 is a flow chart of a method for increasing the efficiency of gas use for an e-chuck according to one embodiment of the present invention.

Fig. 3A is a view illustrating an apparatus for increasing efficiency of a gas for an electrostatic chuck according to one embodiment of the present invention.

Fig. 3B shows an exemplary graph illustrating an electrical signal provided to periodically open and close a valve according to one embodiment of the present invention.

Fig. 4A is a flow diagram of a method for generating a calibration curve for a backside gas at an electrostatic chuck according to one embodiment of the invention.

Fig. 4B shows a graph depicting leak rate versus gas pressure.

Fig. 5 is a flow diagram of a method for increasing the efficiency of a gas for an electrostatic chuck according to one embodiment of the invention.

Fig. 6 is a flow chart of a method for increasing the efficiency of a gas for an electrostatic chuck according to one embodiment of the invention.

Figure 7 illustrates a block diagram of one embodiment of a process chamber system for performing one or more methods for increasing the efficiency of a gas for an electrostatic chuck.

Fig. 8 is a block diagram illustrating an integrated system for increasing the efficiency of a gas for an electrostatic chuck according to one embodiment of the invention.

FIG. 9 shows a block diagram of an exemplary embodiment of a data processing system for performing the methods described herein.

Detailed Description

In the following description, numerous specific details are set forth, such as specific materials, chemistries, dimensions, etc., of the elements, in order to provide a thorough understanding of one or more of the embodiments of the invention. It will be apparent, however, to one skilled in the art that one or more embodiments of the invention may be practiced without these specific details. In other instances, semiconductor fabrication processes, techniques, materials, equipment, etc., have not been described in detail to avoid unnecessarily obscuring the description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.

While certain exemplary embodiments of the invention are described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since modifications may occur to those ordinarily skilled in the art.

Reference throughout the specification to "one embodiment," "another embodiment," or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Furthermore, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention. While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.

Methods and apparatus for increasing the efficiency of gas use in an electrostatic chuck (e-chuck) are described. Gas is received through an inlet. A portion of the gas is supplied to the electrostatic chuck. The remainder of the gas is recirculated back through the flow hole to the compressor to at least one of the inlet and the gas reservoir, rather than being vented out into the vacuum line.

Supplying a first portion of the gas to the electrostatic chuck and recycling a second portion of the gas back to the inlet through the compressor provides an advantage by increasing the efficiency of backside gas use for the e-chuck by at least about 40 times. More than about 95% of the backside gas (BSG) is recirculated back to the inlet and is not vented all the way through the flow holes in the vacuum system. Backside gas usage is reduced to an insignificant amount so that helium can be advantageously used while saving manufacturing costs.

Furthermore, the methods and apparatus for advantageously increasing the efficiency of gas use in an e-chuck as described herein may use existing plasma processing hardware.

Fig. 1 illustrates an apparatus 100 for increasing the efficiency of gas use for an electrostatic chuck according to one embodiment of the invention. The gas supply system 111 comprises a servo 106 having at least two outlets.

In an alternative embodiment, the servo 106 is an automated device that uses negative pressure sensing feedback, negative flow rate sensing feedback, or both to adjust the gas flow to a predetermined set point. The outlet 121 is coupled to the electrostatic chuck 108, and the outlet 122 is coupled to the control valve 107. Gas 101 is flowed to pressure servo 106 through an inlet of gas supply system 111. The gas 101 is a heat transfer gas or any other gas supplied to the e-chuck. In embodiments, the gas 101 is helium, argon, neon, krypton, xenon, other inert gases, nitrogen, or any combination thereof. A portion 102 of the gas 101 is supplied to an electrostatic chuck (e-chuck) 108 through an outlet 121 of a gas servo 106. In an embodiment, the pressure of the portion 102 is adjusted to match a pressure set point at the electrostatic chuck 108. In an embodiment, the pressure set point at the electrostatic chuck 108 is from about 6torr to 30 torr. As shown in fig. 1, a portion 103 of the gas 101 supplied to the control valve 107 through the outlet 122 is recirculated back to the inlet of the gas supply system 111 through the recirculation line 104. In an embodiment, the pressure of the recirculated portion 103 of the gas 101 is increased by a compressor (not shown). In an embodiment, the pressure of the recirculated portion 103 of the gas is increased such that the portion 102 has a pressure that matches the pressure at the inlet. In one embodiment, the pressure at the inlet is from about 10psi to about 25 psi. In a more specific embodiment, the pressure at the inlet is about 15 psi. In an embodiment, after compression by the compressor, the recycled portion 103 of the gas 101 is stored in a gas storage (not shown) for future use.

In an embodiment, control valve 107 is opened for a first time interval to direct portion 103 of gas 101 through the flow orifice to be vented using vacuum pump line 105. The leak rate in the first part of that interval is calculated. In an embodiment, the control valve 107 is closed for a second time interval, greater than the first time interval, in order to direct the portion 103 of the gas 101 to the recirculation line 104, thereby limiting the loss of gas in the vacuum pump line 105. In one embodiment, the frequency of the bleed is adjusted so that a large portion of the gas is fed back to the recycle line.

The e-chuck 108 includes an insulating portion 113 on a conductive base 112. The electrode 114 is embedded in the insulating portion 113 to generate an attractive force to hold the wafer 109. In embodiments, insulating portion 113 is ceramic, polyimide, or any other dielectric material known to those skilled in the art of electronic device manufacturing. In one embodiment, the conductive base 112 is aluminum, other durable metals, other conductive materials, or any combination of the above, as known to those skilled in the art of electronic device manufacturing.

Although fig. 1 depicts one electrode 114, a co-planar pair of electrodes may be embedded within the insulating portion 113 for a bipolar e-chuck. The insulating portion 113 has a top surface for supporting the workpiece 109. With the clamping voltage applied, the workpiece 109 is attracted to the top surface of the chuck 108 and electrostatically clamped to the chuck 108.

In an embodiment, the workpiece 109 is a semiconductor wafer, such as silicon, germanium, or any other semiconductor wafer. In at least some embodiments, the workpiece 109 comprises any material used to fabricate any of integrated circuits, passive (e.g., capacitors, inductors), and active (e.g., transistors, photodetectors, lasers, diodes) microelectronic devices. The workpiece 109 may include insulating (e.g., dielectric) material separating such active and passive microelectronic devices from one or more conductive layers formed on top of the active and passive microelectronic devices. In one embodiment, the workpiece 109 is a silicon ("Si") substrate that includes one or more dielectric layers (e.g., silicon dioxide, desalinized silicon, sapphire, and other dielectric materials). In one embodiment, the workpiece 109 is a wafer stack comprising one or more layers. One or more layers of the workpiece 109 may comprise a layer of a conductive layer, a semiconductive layer, an insulating layer, or any combination of the above.

At least one cooling channel, such as cooling channel 115, is formed through the e-chuck 108 to supply a portion 102 of the gas 101 from the gas supply system 111 to an interstitial space 116 between the backside of the workpiece 109 and the top surface of the chuck 108. In an embodiment, to ensure uniform gas distribution across the backside of the workpiece 109, the top surface of the electrostatic chuck 108 is provided with gas distribution grooves (not shown). One skilled in the art will appreciate that any pattern and arrangement of gas distribution grooves (and the use of grooves at all) is within the scope of embodiments of the present invention. In an embodiment, the pressure of the backside gas used to provide sufficient heat transfer at the e-chuck 108 is from about 6torr to about 30torr, and in a more particular embodiment, about 12 torr.

Fig. 2 is a flow diagram of a method 200 for increasing gas use efficiency for an e-chuck according to one embodiment of the invention. At operation 201, a heat transfer gas is received through an inlet. At operation 202, a first portion of gas is supplied to the e-chuck. At operation 203, a second portion of the gas is recycled to the compressor to at least one of the inlet and the gas reservoir through the flowbore, as described above with reference to fig. 1.

Fig. 3A is a view illustrating an apparatus 300 for increasing the efficiency of a gas for an electrostatic chuck according to one embodiment of the present invention. The apparatus 300 includes an inlet 301 and an inlet valve 302 to receive pressurized gas 331. Pressurized gas 331 represents, for example, helium, argon, neon, krypton, xenon, other inert gases, nitrogen, or any combination of the foregoing. Inlet valve 302 is opened and the flow of gas 331 is then flowed through a flow control section comprising flow meter 303, control valve 304 and pressure sensor 305. In an embodiment, the valve 302 is a pneumatic shut-off valve. In one embodiment, pressure sensor 305 is a Baratron manometer or any other gas pressure measuring device known to those skilled in the art of electronics manufacturing.

In the flow control section, the pressure sensor 305 measures the actual pressure of the gas flow 331. The measured pressure is compared to a predetermined pressure set point and if the measured pressure does not match the predetermined pressure set point, the opening of the control valve 304 is adjusted to match the actual pressure to the pressure set point. The control valve 304 may be one of ordinary skill in the artSolenoid controlled valves or any other control valve known to the skilled person for regulating the pressure of the gas. The flow of gas 331 is monitored by flow meter 303. The flow meter 303 may be a mass flow meter known to those skilled in the art for measuring gas flow (e.g., MKS)

A flow meter) or any other flow meter. The flow meter 303 is calibrated for the particular gas used for backside wafer cooling. In an embodiment, the flow meter 303 is a mass flow controller for measuring the flow rate of the gas 331 and controlling the flow rate of the gas 331 to a given flow rate set point. Downstream of the flow control section, a portion 307 of the gas 331 is directed through the valve assembly 306 to the electrostatic chuck 308. In an embodiment, portion 317 of gas 331 is passed through flow orifice 309 and fed back to inlet valve 302 through a recirculation line. In another embodiment, the flow aperture 309 is positioned between the vacuum valve 311 and the vacuum pump 316 such that there is no flow aperture prior to the recirculation line. In this embodiment, a portion 317 of gas 331 is fed back directly to inlet valve 302 through a recirculation line. In an embodiment, the valve assembly 306 comprises a control valve.

In general, control valves are used to control gas parameters (e.g., flow, pressure) by being opened or closed in response to signals received from a controller that compares set points to actual parameter values provided by sensors that monitor changes in such parameters. The opening or closing of the control valve is typically accomplished automatically by an electronic, hydraulic or pneumatic actuator based on an electrical or pneumatic signal. In an embodiment, valve assembly 306 includes a mass flow controller coupled to a control valve for measuring the flow rate of portion 307 of gas 331 and controlling the flow rate of portion 307 of gas 331 to a predetermined flow rate set point. In an embodiment, the predetermined flow rate set point for portion 307 is in the approximate range of from about 0.2SCCM to about 2SCCM, and in a more particular embodiment is about 0.5 SCCM.

In another embodiment, the valve assembly 306 includes a pressure controller coupled to a control valve. The pressure controller is positioned to regulate the pressure of the gas portion 307 entering the e-chuck 308. When the actual pressure reading is less than the set point value, the pressure controller opens the control valve to increase the amount of gas entering the e-chuck. When the valve is opened, the gas portion 307 enters the e-chuck, and thus the pressure rises to meet the set point value. When the actual pressure reading is greater than the set point value, the pressure controller closes the valve to reduce the amount of gas 307 entering the electrostatic chuck 308. When the valve is closed, less gas enters the electrostatic chuck 308 and thus the pressure drops to meet the set point value.

The recirculation line includes a control valve 312. Control valve 312 opens to direct portion 317 to compressor 313. As described above, the pressure of portion 317 of gas 331 is increased by the compressor. In an embodiment, trigger signal 315 is sent to turn on the compressor. A trigger signal is sent to the compressor to indicate the presence of gas in the recirculation line. The compressed portion 317 of gas 331 is stored in gas reservoir 314. Gas is supplied from the gas reservoir 314 back to the inlet valve 302 through the valve 332. In an embodiment, portion 317 of gas 331 is directed through flow hole 309 to a vacuum line connected to vacuum pump 316. In an embodiment, the vacuum line includes a control valve that opens to supply a portion 317 of gas to the vacuum pump 316 such that a controlled "bleed" of gas portion 317 to vacuum is provided through flow aperture 309. In an embodiment, flow orifice 309 is a fixed flow orifice. In another embodiment, flow orifice 309 is an adjustable flow orifice.

Generally speaking, the purpose of bleed-out is to ensure that the pressure control system is not "dead-ended". Because leakage across the wafer is typically very low, the controlled bleed provides additional pressure relief for faster response to the pressure set point. The size of the flow orifice 309 depends on the range of gas flow measured by the flow meter 303. Typically, the larger the gas flow measured by the flow meter, the larger the size of the flow orifice.

In one embodiment, portion 317 of gas 331 is fed through the flow holes for a first time interval to bleed out on the vacuum line, and portion 317 of gas 331 is fed to the recirculation line back to the inlet for a second time interval. In an embodiment, to limit gas losses, the bleed line is opened during a time interval that is less than the time interval during which the recirculation line is opened. In an embodiment, an electrical signal is sent to close valve 311 and open valve 312 to feed gas back to the inlet through the recirculation path. In an embodiment, an electrical signal is sent to close valve 312 and open valve 311 to feed gas through the bleed vacuum line.

Fig. 3B shows an exemplary graph 310, which graph 310 illustrates an electrical signal provided to periodically open and

close valves

311 and 312, according to one embodiment of the present invention. Graph 310 is a graph representing amplitude 322 versus time 321 of an electrical signal. For example, curve 323 represents a signal for opening valve 311 during time interval 324 and closing valve 311 during time interval 325. For example, curve 326 represents a signal for closing valve 312 during time interval 324 and opening valve 312 during time interval 325. In an embodiment, time interval 325 is greater than time interval 324. In another embodiment, time interval 325 is less than time interval 324. In yet another embodiment, time interval 325 is similar to time interval 324. In an embodiment, the time interval 324 during which the vacuum line is opened to vent gas is greater than about 3 seconds. In an embodiment, the time interval 325 during which the recirculation line is opened is greater than about 3 seconds. In a more particular embodiment, time interval 325 is about 60 seconds.

Fig. 4A is a flow diagram of a method 400 for generating a calibration curve for a backside gas at an electrostatic chuck, in accordance with one embodiment of the invention. At operation 401, gas is supplied through an inlet. The gas is one of the gases described above. At operation 402, a flow rate of gas through the flow hole is measured at a plurality of pressure values while the gas is directed to the vacuum line through the fixed flow hole. In an embodiment, the flow rate of the gas is measured using a flow meter (such as the flow meter 303 depicted in fig. 3). The pressure value of the gas entering the e-chuck is measured using a pressure sensor, such as pressure sensor 305. The flow rate of the portion of the gas flowing through the flow orifice to the vacuum line is determined by the flow orifice size. In this embodiment, the flow rate of the portion of the gas at the e-chuck (leak rate) is calculated as the difference between the measured flow rate and the flow rate of the gas flowing through the flow orifice to the vacuum line. In another embodiment, leak rates are measured at a plurality of pressure values collected using a valve assembly (such as valve assembly 306). At operation 403, a calibration curve is generated that displays the leak rate as a function of the pressure value. At operation 404, the calibration curve is stored in a memory of the data processing system.

Fig. 4B shows a graph 410 depicting leak rate 412 versus gas pressure 411. As described above with reference to fig. 4A, the calibration curve 413 for the gas is generated by measuring the flow rate at a plurality of pressure values. A calibration curve is used to estimate leak rate values for a predetermined pressure set point. As shown in fig. 4B, the leak rate value for pressure set point 414 is value 415, according to curve 413.

Fig. 5 is a flow diagram of a method 500 for increasing the efficiency of a gas for an electrostatic chuck, according to one embodiment of the invention. At operation 501, a pressure set point for a gas at an electrostatic chuck is determined. The pressure set point is the backside gas pressure at which the desired heat transfer is achieved at the e-chuck. The pressure set point for the gas at the e-chuck may be determined, for example, from a plasma process recipe stored in a memory of the data processing system. At operation 502, a calibration curve for a gas is determined. In one embodiment, the calibration curve for the gas is retrieved from a memory of the data processing system. At operation 503, the flow rate of the gas at the e-chuck (leak rate) is estimated using the calibration curve and the pressure set point, as described above. At operation 504, gas is received through the inlet as described above. At operation 505, a first portion of gas is supplied to the e-chuck as described above. At operation 506, a second portion of the gas is supplied to the vacuum line through the flow hole, as described above. At operation 507, it is determined whether the flow rate (leak rate) of the gas at the electrostatic chuck matches the estimated flow rate. The leak rate may be measured using a valve assembly, such as the valve assembly 306 depicted in fig. 3. If the measured leak rate does not match the estimated leak rate, the method 500 returns to operation 506. If the measured leak rate matches the estimated leak rate such that the leak rate is stabilized, then at operation 508, a second portion of the gas is supplied to the recycle line as described above. At operation 509, a determination is made as to whether a trigger signal is received by the compressor. A trigger signal is sent to the compressor to indicate the presence of gas in the recirculation line. If a trigger signal is received by the compressor, at operation 510, the compressor is opened to increase the pressure of the gas in the recirculation line, as described above. If a trigger signal is not received by the compressor, the method 500 returns to operation 504. At operation 511, the compressed second gas portion is stored in a gas reservoir, as described above.

Fig. 6 is a flow diagram of a method 600 for increasing the efficiency of a gas for an electrostatic chuck, in accordance with one embodiment of the invention. At operation 601, gas is received through an inlet as described above. At operation 602, a valve (such as valve 311) for directing gas through the flow hole to the vacuum line is opened for a first time interval as described above. At operation 603, a flow rate (leak rate) of the gas at the electrostatic chuck is estimated. As described above with reference to fig. 4A and 4B, leak rate may be estimated by measuring gas flow at a plurality of pressure values to obtain a calibration curve. At operation 604, the valve to the vacuum line is closed for a second time interval as described above. At operation 605, a first portion of the gas is supplied to the e-chuck at the estimated leak rate, as described above. At operation 606, a second portion of the gas is recycled back to the inlet as described above. At operation 607, it is determined whether a leak rate at the e-chuck needs to be checked. If a leak rate at the e-chuck needs to be checked, the method 600 returns to operation 603. If there is no need to check for leak rate at the e-chuck, the method 600 continues at operation 608, which involves recirculating a second portion of the gas back to the inlet, as described above.

Fig. 7 illustrates a block diagram of one embodiment of a process chamber system 700, the process chamber system 700 for performing one or more methods for increasing the efficiency of a gas for an electrostatic chuck as described above. As shown in fig. 7, the system 700 has a process chamber 701, the process chamber 701 including a temperature controlled electrostatic chuck pedestal 702. The workpiece 703 is placed on the electrostatic chuck base 702. Workpiece 703 represents one of the plurality of workpieces described above. The workpiece 703 is loaded through the opening 718 and clamped to the temperature controlled electrostatic chuck 702. In an embodiment, a gas 704 is passed between the ESC 702 and the workpiece 703. Gas 704 represents one of the various gases described above. As described above, the DC electrode 708 is embedded in the electrostatic chuck 702. A DC power supply 724 is connected to the DC electrode 708. A plurality of cooling channels 709 are formed to supply gas 704 from a gas supply system 717. The gas supply system represents one of the systems depicted in fig. 1 and 3.

A plasma 707 is generated from one or more process gases 716 using a high frequency electric field. As shown in fig. 9, the pressure control system 723 provides pressure to the process chamber 701 and the DC bias power supply 724 provides a DC bias voltage to the DC electrode 708. As shown in fig. 7, the chamber 701 is coupled to an RF source power 706 and to two RF bias powers 720 and 721 to generate a plasma 707. At least one of RF bias powers 720 and 721 is applied to the ESC 702 to generate a directed electric field in the vicinity of the workpiece. The chamber 701 is evacuated through the exhaust outlet 710. The exhaust outlet 710 is connected to a vacuum pumping system (not depicted) for evacuating volatile compounds generated in the chamber during processing. As shown in fig. 7, process gas 716 is supplied to the chamber 701 through a mass flow controller 725. When plasma power is applied to chamber 701, a plasma 707 is formed in the processing region above workpiece 703. Plasma bias power 720 is coupled to the chuck 702 via an RF match 719 in order to energize the plasma. The plasma bias power 720 typically has a frequency between about 2MHz to about 60 MHz. Plasma bias power 721 (e.g., operating at about 2MHz to about 60 MHz) may also be provided to provide dual frequency bias power. Plasma source power 706 is coupled to the plasma generating component 705 (e.g., showerhead) to provide high frequency source power to energize the plasma. The plasma source power 706 typically has a higher frequency than the plasma bias power 720 and, in a particular embodiment, is in the 60MHz band. In an embodiment, the plasma chamber 701 is a capacitively coupled plasma chamber. In another embodiment, the plasma chamber 701 is an inductively coupled plasma chamber.

As shown in fig. 7, the system 700 includes a controller 711 coupled to the chamber 701 to perform one or more methods as described herein. The controller 711 includes: a processor 712, a temperature controller 713 coupled to the processor 712, a memory 714 coupled to the processor 712, and an input/output device 715 coupled to the processor 712. In an embodiment, the memory 714 is configured to store a calibration curve for determining a leak rate of gas at the e-chuck, as described above. The controller 711 may be software or hardware or a combination of both. The processing system 700 may be any type of high performance semiconductor processing chamber known in the art, such as, but not limited to, a chamber manufactured by applied materials, Inc. of Santa Clara, Calif. Other commercially available semiconductor chambers may be used to perform the methods as described herein.

Fig. 8 is a block diagram of an integrated system 800 for increasing the efficiency of gas for an e-chuck according to one embodiment of the invention. System 800 includes a plurality of subsystems, such as subsystem 801 and subsystem 802. Each of the subsystems includes multiple process chambers (such as chamber 803). The chamber 803 may be a process chamber as depicted in fig. 7 or any other process chamber. Each of the processing chambers includes an e-chuck (such as e-chuck 804). The e-chuck 804 represents one of a plurality of e-chucks described herein. Gas is supplied to each of the e-chucks by a gas supply system, such as gas supply system 805. The gas supply system 805 represents the gas supply system 111 depicted in fig. 1, or any other gas supply system for increasing the efficiency of gas use for an e-chuck as described herein. Each gas supply system has an inlet, such as inlet 806, for receiving gas. Each gas supply system has an outlet to supply a portion of the received gas to a corresponding e-chuck as described herein. Each gas supply system has an outlet to recirculate 807 a portion of the gas back to the inlet through a recirculation line (such as recirculation line 809), as described above. A compressor 811 is coupled to each of the plurality of recirculation lines to increase the pressure of the recirculated portion of the gas, as described herein. A gas reservoir 812 is coupled to the compressor 811 to store pressurized gas as described herein. Pressurized gas 813 is supplied from the reservoir back to the inlet of each of the gas supply systems, such as system 805. A controller 814 is coupled to control each of the gas supply inlet, outlet, compressor, and gas reservoir to perform the methods described herein.

FIG. 9 shows a block diagram of an exemplary embodiment of a data processing system 900 for performing the methods described herein. The data processing system process 900 represents a controller 711, a controller 814, or any other data processing system for controlling increasing the efficiency of a gas for an electrostatic chuck as described herein with reference to fig. 1-8. In alternative embodiments, the data processing system may be connected (e.g., networked) to other machines in a Local Area Network (LAN), an intranet, an extranet, or the internet. The data processing system may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment.

A data processing system may be a Personal Computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that data processing system. Moreover, while only a single data processing system is illustrated, the term "data processing system" shall also be taken to include any collection of data processing systems that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies described herein.

The exemplary data processing system 900 includes a processor 902, a main memory 904 (e.g., Read Only Memory (ROM), flash memory, Dynamic Random Access Memory (DRAM), such as synchronous DRAM (sdram) or Rambus DRAM (RDRAM), etc.), a static memory 906 (e.g., flash memory, Static Random Access Memory (SRAM), etc.), and a secondary memory 918 (e.g., a data storage device), which communicate with each other via a bus 930.

Processor 902 represents one or more general-purpose processing devices such as a microprocessor, central processing unit, or other processing device. More particularly, the processor 902 may be a Complex Instruction Set Computing (CISC) microprocessor, Reduced Instruction Set Computing (RISC) microprocessor, Very Long Instruction Word (VLIW) microprocessor, processor implementing other instruction sets, or processors implementing a combination of instruction sets. The processor 902 may also be one or more special-purpose processing devices such as an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), network processor, or the like. The processor 902 is configured to control the processing logic 926 for performing the operations described herein with reference to fig. 1-8.

The computer system 900 may further include a network interface device 908. Computer system 900 may also include a video display unit 910, an alphanumeric input device 912 (e.g., a keyboard), a cursor control device 914 (e.g., a mouse), and a signal generation device 916 (e.g., a speaker).

The secondary memory 918 may include a machine-accessible storage medium (or, more specifically, a computer-readable storage medium) 921 on which is stored one or more sets of instructions (e.g., software 922) embodying any one or more of the methodologies or functions described herein. The software 922 may also reside, completely or at least partially, within the main memory 904 and/or within the processor 902 during execution thereof by the data processor system 900, the main memory 904 and the processor 902 also constituting machine-readable storage media. The software 922 may further be transmitted or received over a network 920 via the network interface device 908.

While the machine-accessible storage medium 921 is shown in an exemplary embodiment to be a single medium, the term "machine-readable storage medium" should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term "machine-readable storage medium" shall be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present invention. The term "machine-readable storage medium" shall accordingly be taken to include, but not be limited to, solid-state memories and optical and magnetic media.

In the foregoing specification, embodiments of the invention have been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made to these embodiments without departing from the broader spirit and scope of the embodiments of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Claims

1. A method for increasing the efficiency of a backside gas for an electrostatic chuck, the method comprising:

receiving the gas through an inlet;

supplying a first portion of the gas to the electrostatic chuck;

recirculating a second portion of the gas through a compressor;

determining a pressure set point for the gas at the electrostatic chuck;

obtaining a calibration curve for the gas;

estimating a flow rate of the first portion of the gas for the pressure set point based on the calibration curve; and

controlling the first portion of the gas based on the estimated flow rate.

2. The method of claim 1, wherein the gas is helium, argon, neon, krypton, xenon, nitrogen, or any combination thereof.

3. A method for increasing the efficiency of a backside gas for an electrostatic chuck, the method comprising:

receiving the gas through an inlet;

supplying a first portion of the gas to the electrostatic chuck;

recirculating a second portion of the gas through a compressor; and

measuring the flow of the gas at a plurality of pressure values to generate a calibration curve.

4. The method of claim 3, wherein the gas is helium, argon, neon, krypton, xenon, nitrogen, or any combination thereof.

5. A method for increasing the efficiency of a backside gas for an electrostatic chuck, the method comprising:

receiving the gas through an inlet;

supplying a first portion of the gas to the electrostatic chuck;

recirculating a second portion of the gas through a compressor;

determining whether to supply the gas through the inlet; and

sending a trigger signal to the compressor if the gas is supplied to the inlet.

6. The method of claim 5, wherein the gas is helium, argon, neon, krypton, xenon, nitrogen, or any combination thereof.